1. Field
The present disclosure relates to a speaker device and a microphone device including a vibration unit in which a ribbon-like diaphragm is disposed in a magnetic gap.
2. Description of the Related Art
Conventional examples of a vibration unit included in a speaker device, a microphone device, or the like, include the one proposed in JP 55-25231 A. In that vibration unit, a plurality of parallel conductors is formed on a diaphragm disposed in a magnetic gap, both end portions of the diaphragm are vibratably supported by a frame, and connection terminals formed on the frame are connected to the plurality of parallel conductors, whereby these components cooperate to function as a coil in the magnetic gap.
The diaphragm is a ribbon-like thin film member including a synthetic resin material such as nylon, and a plurality of parallel conductors including aluminum or the like is formed on the diaphragm. The frame includes an insulating material having high rigidity, and the diaphragm is disposed while being bent in a zigzag shape in a notch provided at the center of the frame. A pair of connection conductors and a plurality of terminals are provided in the frame so as to surround the notch. By superimposing the diaphragm and the frame such that conductor forming surfaces thereof face each other, the parallel conductors are each connected to an end portion of the connection conductor and the terminal to form a coil.
In a case where the vibration unit configured as described above is applied to a microphone device, when the diaphragm vibrates within the magnetic gap upon receiving sound pressure, a plurality of parallel conductors formed on the diaphragm crosses magnetic fluxes. As a result, an electromotive force is generated between the terminals of the frame by the electromagnetic induction action. In addition, in a case where the vibration unit having the above configuration is applied to a speaker device, when an audio signal is input between the terminals of the frame, currents in the same direction flow through the plurality of parallel conductors formed on the diaphragm. As a result, the diaphragm vibrates in a direction orthogonal to the plate surface thereof and the sound pressure is generated.